AR 90 question

[Guest]

I have a pair of old AR 90s that I bought new 22 years ago as part of a system that included Phase Linear amp, preamp, eq and a Technics turntable.

The speakers are still in excellent condition and, in fact, care currently being used as mains in a home theater system (with Adcom amps). In cleaning them this past weekend, I discovered some small cracks in the foam surrounds in the woofers.

I should say upfront that I am not an engineer or technically very knowledgable. Just someone who loves good jazz and nice equipment.

In searching for a place to repair the surrounds, I stumbled across this forum. After reading many of the posts, my question is what exactly is the difference between my AR 90s and a pair of AR 9s? I gather that the 9s have much superior bass, but I'm not able to determine much beyond that.

There seems to be lots of posts about the 9s and very little about the 90s. I understand this is because the 90s are less desirable, but since many of the components seem to be the same, I'm not sure exactly why.

I should add that I have no interest in selling them. I'm just curious about how the two compare. And since I'm at a point of needing to replace the foam anyway, whether or not the 90s can (or even should be ) upgraded to sound as good as many indicate the 9s sound. Thanks in advance for any input.

[ar_pro]

The Nines used two of the nominal 12" woofers that had been developed from the AR-1, through the 3 and 3a, LST, 10pi, and 11. The low-frequency capability of this design was unequalled by any other AR system.

The 90 matched a pair of 10" woofers with the other Model 9 drivers in a smaller enclosure, and used a different crossover network.

Similarities in sound would far outweigh the differences between the two systems, with bass extension (although the 90 is no slouch!) and spl characteristics being primary.

The 90 is a beautiful system, especially in a slightly smaller room, and Adcom amplification is commonly considered to be a very nice match!

Be sure to check your 8" drivers...if they are original, they will almost certainly need to be re-foamed, too.

[Guest]

Thanks for responding. A couple of additional follow up questions if you don't mind:

First, what is the optimum size room for the 90s and what would be considered too large?

Also, in talking with someone at Layne about refoaming, I asked what additional upgrades I should consider while I'm at it to improve the sound quality (this was before reading some of the posts here). The suggestion was to also swap out the mids and tweeters with Dyne Audio (sp?) mids and tweeters. In your opinion, what would I gain by that, and what would I lose, aside from perhaps spending more than I would see in improved performance?

[ar_pro]

That's a tough one - I don't think that there are any absolute rules concerning the optimum size of a room for a given loudspeaker...things like the type of music played, desired volume level, seating location, acoustical characteristics of the listening space, available amplification, etc. are all factors, too. Simply stated, the attributes of the 90 could be carried over into a larger space with the AR-9 (all other variables being equal).

If you take a look at some of the previous posts regarding the "upgraded parts" controversy (mostly concerning the 3a, I believe), you'll pretty much find two schools of thought:

1.) Newer drivers will improve the sound of a classic speaker.

and

2.) Newer drivers will change the sound of a classic speaker, and it will no longer be a classic speaker.

My hunch is that most fans of this site would be behind making non-intrusive changes (things like using heavier gauge internal wiring, soldering connections instead of friction-fitting them, and maybe adding spikes to the floor-standing models), but would balk at pulling out their working vintage drivers in order to replace them with a new Danish dome tweeter whose main attribute is that it would fit the hole.

There are a number of well thought-out posts from Tom Tyson and others, that effectively question the assumption that a newer driver would be inherently better than what AR built 25 years ago!

[Guest Sean]

>Also, in talking with someone at Layne about refoaming, I

>asked what additional upgrades I should consider while I'm

>at it to improve the sound quality (this was before reading

>some of the posts here). The suggestion was to also swap out

>the mids and tweeters with Dyne Audio (sp?) mids and

>tweeters. In your opinion, what would I gain by that, and

>what would I lose, aside from perhaps spending more than I

>would see in improved performance?

My suggestion is to obviously check into foam rot and refoam as necessary. Layne audio is a good source for doing so and i do recommend Steve as he is both good at what he does and fair in price.

The next steps would be to replace all of the existing factory capacitors and internal wiring with something more appropriate. This will make a HUGE difference in terms of system transparency and dynamics.

If one wants to tackle replacing the inductors ( coils ), it is the least cost effective thing to do. As such, i would leave it for last and see if you can live with the OEM models.

Once you've reached this level, most of the "problems" in your system will revolve around speaker placement / room acoustics and the limiting factors upstream of the speakers. Sean

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[Guest Nigel]

>The next steps would be to replace all of the existing

>factory capacitors and internal wiring with something more

>appropriate. This will make a HUGE difference in terms of

>system transparency and dynamics.

I have to dis-agree here. At the time the AR9x family was produced, AR was using excellent caps. There will not be a HUGE difference in doing this, and if you don't go with the highest grade caps available (rather expensive) you may make things worse. Larger, higher quality wire may or may not make an audible difference to you.

>If one wants to tackle replacing the inductors ( coils ), it

>is the least cost effective thing to do. As such, i would

>leave it for last and see if you can live with the OEM

>models.

And here. Replacement inductors comparable the air core ones in your AR90 speakers are very expensive, and better ones are even more so. AR use 17 guage wire in thier inductors, meaning you will have to go to 14 guage wire air core inductors to even electrically measure much of a difference, and then the resistance of the circuit would be different, changing it performance, so you'd have to compensate for that to. In other words; don't.

>Once you've reached this level, most of the "problems" in

>your system will revolve around speaker placement / room

>acoustics and the limiting factors upstream of the speakers.

Here I sort of agree, but most of the "problems" are with placement and room environment right from the start.

Nigel

[Guest]

As a relatively new collector of vintage stereo equipment and current owner of a pair of 3a's, I must add that if you have a pair of good vintage AR speakers, keep them that way. I restored a pair of 2ax's and now the 3a's. Beautiful pieces of furniture and wonderful sounding speakers. Why would you have a restored vintage GTO and replace the engine with one from a Ford.It wouldn't be the same car. I feel if you've recovered something vintage or maybe owned one from the beginning, give it as long a life as humanly possible. They are irreplaceable pieces of our history. Definately refoam and just replace that which needs replacing. Just my humble opinion.

[Guest Sean]

Nigel: I would ask "how many different brands of caps have you listened to ? "

I would also ask "Do you think that series resistance is the only criteria that matters in a coil other than inductance ? "

Technology in capacitors has grown by leaps and bounds since the time that the 9's / 90's were produced.

As far as coils go, read my comments about this in the thread that i started regarding the errors that i've found in the AR 9 schematic. Other than this specific incidence, i think that you'll find that Goertz inductors SMOKE most other coils in head to head comparisons. Sean

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[Guest Sean]

As to your question about "tinkering" with a GTO, that would depend upon your outlook on things. If you looked at the GTO as a classic, it would be "heresy" to even think about doing something like that. If you looked at it as a "hot rod" or "high performance machine", adding / upgrading parts would be considered normal.

These speakers are the same thing. If you want and like "vintage

AR sound", leave them alone. If you want to improve upon what was a good but now dated design, have at it. Technology has moved on but that does not mean that personal preferences have changed. Sean

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[Guest]

Again, please pardon a rookie question, but what exactly is the "vintage AR sound" as compared with newer high end speakers, such as Bower & Wilkins, for instance?

[Guest Sean]

It is hard to put something like this into words, especially since both companies ( AR & B&W ) have made so many different models. My thoughts would be that the "vintage" AR sound would be warmer and more congested sounding than that of most B&W's. The B&W will sound more open and lively whereas the AR's will sound more sluggish in terms of speed and transparency. Much of this has to do with tonal balance rather than actual transient response though. The deficiencies in most "vintage" AR designs are pretty easy to overcome though, as they simply need to be updated in terms of cabinet bracing, internal wiring and upgraded capacitors. Doing these simple yet highly effective mods will drastically alter your perception of the "old" AR's. Sean

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